1. Field of the Invention
The present invention relates to air compressors and more particularly to an air compressor with a source of UV light located within the tank which when energized disinfects the internal surfaces of the tank illuminated by the light source.
2. Description of Prior Art Including Information Disclosed Under 37 Cfr 1.97 and 1.98
It is known that ultraviolet (UV) irradiation can effectively inactivate certain types of bacteria. Low pressure mercury lamps emitting ultraviolet light with a wavelength of 254 nm have been used for that purpose. However, mercury can be harmful and a lamp containing mercury can pose a hazard if subjected to shock or vibration. Accordingly, such lamps are not suitable for certain applications, including use in pressurized environments or where the lamp may be subject to vibrations.
It is also known that ultraviolet light-emitting diodes (LEDs) with certain output wavelengths and sufficient power have the ability to sterilize liquids. For example, a UV LED with an output wavelength of 365 nm may function as an effective sterilization device, see M. Mori et al., Medical Biological Engineering Computer Journal, (2007) 45: 1237-1241 entitled: “Development of a new water sterilization device with a 365 nm UV-LED”. Further, Nikkiso America, Inc. of San Diego, Calif. sells UV LEDs which can be used for disinfecting water and sewerage.
In many dental and medical applications it is important to insure that the air supply to devices used to treat patients and in the presence of practitioners be as clean and germ free as possible. Air compressors are commonly used to supply air in such situations. To keep the air supply as clean as possible, various devices have been used to prevent air “backflow” from patients into the compressor. Further, various filtration and dehumidification methods have been employed to keep the air to the compressor as clean and dry as possible.
However, over time, bacteria and other organisms tend to form a film on the internal surface of the compressor tank. Those bacteria and organisms can contaminate the air being pumped from the compressor. Accordingly, there is a need to have a mechanism capable of continuously disinfecting the internal surfaces of the compressor tank without having to periodically dismantle or otherwise interrupt the operation of the compressor. Mercury lamps of the aforementioned type are not suitable for use in such an environment due to the pressure and vibration, the dangers associated with the use of a toxic substance and other factors.
Although numerous UV LEDs are currently commercially available, they are not effective as antibacterial devices because they are low power and emit in the 380 nm to 400 nm wavelength range. As mentioned above, mercury lamps that emit at the 254 nm wavelength can be very effective for sterilization and disinfection. However, mercury lamps cannot be used in a high pressure or high vibration environment.
Harnessing the UV LEDs discussed by Mori et al. or sold by Nikkiso America, Inc. for use in disinfecting the internal surface of the compressor tank would be a significant improvement if certain technical difficulties associated with this environment are overcome. Ports can be created in the compressor tank wall to allow for the placement of one or more LEDs inside the tank. The LEDs can be oriented in a fashion which bathes the interior with germicidial UV light. The LEDs are strong enough to withstand the vibrations encountered in compressor operation.
The effectiveness of the LEDs can be maximized by directing the light from the LEDs to the areas of the tank where liquid tends to accumulate and hence where germs are most likely to grow. Spreading out the light beam from the LEDs to provide wider coverage can be achieved through the use of lenses. Mirrors and baffles may be used to direct the light as needed.
A protective cover made of quartz or similar situated between the LED and the air in the compressor tank can be used to protect the LED from the environment within the compressor tank. Preferably, the cover can take the form of a divergent lens which can shape the light beam as needed, thereby combining the protective and beam shaping qualities in a single component. Covers/lenses fabricated of other materials such as certain glasses and polymers may be used for this purpose, as well.
Over time, dust and other particles may settle on the LED or the cover/lens of the LED. This will reduce the effective output of the LED by absorbing some of the energy that would otherwise be available for germicidal effect. That energy is converted to heat and is re-emitted as IR radiation which is not useful in this situation.
This problem can be greatly reduced by utilizing a structure within the compressor tank which preferentially directs some of the incoming (or outgoing) airflow across the surface of the LED (or the cover/lens thereof) so as to continuously remove dust and other particles. This structure may take the form of stationary internal baffles, guides or vanes which create turbulence, vortexes or venturi in the area proximate the device. Alternately, a more complex structure such as an internal miniature turbine and fan blade may be employed. In the case of the latter, the turbine rotates due to a pressure differential between the air in the chamber and the moving incoming (or outgoing) air. These may be placed below pistons or other pressurizing mechanisms so that the temporary pressure differentials within the chamber cause air movement as described above. The motion of this air need not be continuous but may occur during part of the compression cycle or start up pressurization or, possibly, de-pressurization.
Further, it is believed that pulsing the light output from the UV LEDs may increase the sterilization effect of the light source means. This can be accomplished by a simple control circuit which switches the power to the UV LED on and off at a set frequency for a pre-determined duration.
It is therefore a prime object of the present invention to provide a compressor with an internal disinfecting mechanism.
It is another object of the present invention to provide a compressor with an internal disinfecting mechanism in the form of UV light source.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light source is a UV LED with an output wavelength of at least 250 nm.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light source is a UV LED with an output wavelength of not more than 365 nm.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light source is a UV LED with an output wavelength within the range of 250 nm to 365 nm.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light source is a UV LED with a preferred output wavelength within the range of 260 nm to 270 nm.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light output from the UV LED light source is pulsed.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the light source is protected from the internal environment of the compressor by a cover or lens made of quartz, glass or polymer.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source wherein the beam from the light source is directed to portions of the internal surface of the compressor where liquid tends to pool.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source having means for removing dust or other particles from the path of light from the light source.
It is another object of the present invention to provide a compressor with an internal disinfecting UV light source having means for removing dust or other particles from the path of light from the light source in the form of a structure for creating air turbulence proximate the surface of the light source.